The present disclosure is directed to printing systems, and in particular to method and apparatus for measuring toner concentration in a developer material.
In a typical electrophotographic printing process, an electrostatic latent image on a photoconductive member corresponding to an original document is developed by bringing a developer material into contact with the photoconductive member. Generally, the developer material includes toners adhering triboelectrically to carrier granules. The toners are attracted from the carrier granules to the latent image forming a toner image on the photoconductive member. The toner image is then transferred from the photoconductive member to a copy sheet. The toners are then heated to permanently affix the toner image to the copy sheet.
U.S. Pat. No. 6,449,441 to Koji Masuda discloses a supplying device for supplying toner and carrier to a developer container in conformity with an output of a detector where an intensity of an electric field for shifting the carrier from the developer bearing member to an image bearing member is greater than an intensity of an electric field formed between a nonimage portion of the electrostatic latent image formed on the image bearing member and the developer bearing member.
U.S. Patent Publication No. 2003/0228157 to Seung-Young Byun et al. discloses a method of detecting toner depletion in an image forming apparatus that includes comparing an accumulation pixel number Qt that is obtained by accumulating and counting a number of pixels of a printed image with a reference pixel number Qr calculated from an amount of toner received in a developing unit, and recognizing that the image forming apparatus is in a toner low state if the accumulation pixel number Qt is larger than the reference pixel number Qr.
U.S. Pat. No. 6,687,477 to Motoharu Ichida et al. discloses a toner recycling control system that stably feeds a liquid developer of an appropriate concentration to a liquid developing apparatus employing a high-viscosity liquid developer, appropriately adjusts the concentration of residual developer collected after development and after transfer, and feeds the adjusted developer to the developing apparatus.
U.S. Pat. No. 6,606,463 to Eric M. Gross et al. discloses a toner maintenance system for an electrophotographic developer unit that includes a sump for storing a quantity of developer material including toner material, a first member for transporting developer material from sump, a viewing window in communication with toner material in the sump, an optical sensor for measuring reflected light off the viewing window and toner material, and generating a signal indicative thereof.
U.S. Pat. No. 6,571,071 to Yuichiro Kanoshima et al. discloses an integration density acquiring unit for a consumption information management apparatus that acquires integration density from an image signal sent from an image processing section, and an information converting unit that calculates a quantity of consumer toner by multiplying the integration density by a specified coefficient to send the quantity to a cumulative consumption information calculating unit.
U.S. Pat. No. 6,496,662 to John Andrew Buchanan discloses a toner chamber having a transparent window at its bottom, and a reflective surface also at the bottom. An optical emitter and receiver periodically senses for returned light, which indicates toner low.
U.S. Pat. No. 6,377,760 to Yoshihiro Hagiwara discloses a toner concentration measuring apparatus that measures a concentration of a toner in a developer and having a first and second light guiding devices whose end surfaces project into a duct traversed by developer fluid, and a light receiving device for receiving light transmitted from the first light guiding device to the second light guiding device.
U.S. Pat. No. 6,370,342 to Tomohiro Masumura discloses a toner concentration sensor that has a pair of optical members for optically coupling a light emitting device and a photodetector. The optical members are disposed with a gap therebetween for introducing liquid developer to measure transparency of the liquid developer and to evaluate the toner concentration.
U.S. Pat. No. 6,289,184 to Yong-Baek Yoo et al. discloses a developer film forming device for forming a developer film and a sensing device including a light source unit for emitting colored light corresponding to a range of wavelengths for which light transmissivity is relatively low to a developer film of a selected color developer, and a photodetector for receiving the light emitted by the light source unit and transmitted through the developer film. Thus, a thin developer film is formed and the concentration of developer is measured by emitting light in the range of wavelengths.